1m6s

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Revision as of 01:45, 25 November 2007

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spinqualitylabelsall models 1m6s, resolution 1.8Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

Crystal Structure Of Threonine Aldolase

Overview

L-Threonine acetaldehyde-lyase (threonine aldolase, TA) is a, pyridoxal-5'-phosphate-dependent (PLP) enzyme that catalyzes conversion of, L-threonine or L-allo-threonine to glycine and acetaldehyde in a secondary, glycine biosynthetic pathway. X-ray structures of Thermatoga maritima TA, have been determined as the apo-enzyme at 1.8 A resolution and bound to, substrate L-allo-threonine and product glycine at 1.9 and 2.0 A, resolution, respectively. Despite low pairwise sequence identities, TA is, a member of aspartate aminotransferase (AATase) fold family of PLP, enzymes. The enzyme forms a 222 homotetramer with the PLP cofactor bound, via a Schiff-base linkage to Lys199 within a domain interface. The, structure reveals bound calcium and chloride ions that appear to, contribute to catalysis and oligomerization, respectively. Although, L-threonine and L-allo-threonine are substrates for T. maritima TA, enzymatic assays revealed a strong preference for L-allo-threonine., Structures of the external aldimines with substrate/product reveal a pair, of histidines that may provide flexibility in substrate recognition., Variation in the threonine binding pocket may explain preferences for, L-allo-threonine versus L-threonine among TA family members.

About this Structure

1M6S is a Single protein structure of sequence from Thermotoga maritima with CA and CL as ligands. Active as Threonine aldolase, with EC number 4.1.2.5 Full crystallographic information is available from OCA.

Reference

X-ray structures of threonine aldolase complexes: structural basis of substrate recognition., Kielkopf CL, Burley SK, Biochemistry. 2002 Oct 1;41(39):11711-20. PMID:12269813

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